As shown in FIG. 1, a wireless communication system comprises elements such as client terminal or mobile station 12 and base stations 14. Other network devices that may be employed, such as a mobile switching center, are not shown. In some wireless communication systems, there may be only one base station and many client terminals while in some other communication systems such as cellular wireless communication systems there are multiple base stations and a large number of client terminals communicating with each base station.
As illustrated, the communication path from the base station (BS) to the client terminal direction is referred to herein as the downlink (DL) and the communication path from the client terminal to the base station direction is referred to herein as the uplink (UL). In some wireless communication systems, the client terminal or mobile station (MS) communicates with the BS in both DL and UL directions. For instance, this is the case in cellular telephone systems. In other wireless communication systems, the client terminal communicates with the base stations in only one direction, usually the DL. This may occur in applications such as paging.
The base station to which the client terminal is communicating with is referred as the serving base station. In some wireless communication systems, the serving base station is normally referred as the serving cell. The terms base station and a cell may be used interchangeably herein. In general, the cells that are near the serving cell are called neighbor cells. Similarly, in some wireless communication systems a neighbor base station is normally referred as a neighbor cell.
The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) wireless communication system is one of the widely deployed wireless technologies. The power consumption in the client terminal is one of the important design considerations in 3GPP LTE wireless communication system. Generally, the power consumption may be divided into two categories. The power consumed by the client terminal when it is in active mode such as when in a voice call, a video call, messaging, or internet browsing. The power consumed when the client terminal is in standby mode when it may be only monitoring the paging messages periodically.
When in standby mode, the client terminal is required to receive and decode paging messages in order to be able to respond to any possible incoming calls or data transfers. To reduce the power consumption during standby mode, the client terminal may be configured to receive and decode the paging messages at regular intervals. This is referred to as Discontinuous Reception (DRX) cycle. An example scenario may be that one paging message may need to be decoded by the client terminal once every second. The reception of a single paging message may be performed over a duration of one millisecond. The power consumption in standby mode of the client terminal may be determined by two factors: the power consumed by the client terminal when it is receiving and decoding a paging message and the power consumed due to leakage when the client terminal is in sleep mode when it may turn off most of its components. The sleep mode is a sub-mode within the standby mode of a client terminal. This scenario is illustrated in FIG. 2. The average power consumed by the client terminal is the weighted average of the power consumed during the sleep mode and the power consumed during paging message(s) reception. In the present disclosure, the term standby mode is used to refer to the lower power mode of the modem and RF subsystems. A client terminal may have other subsystems which may have their own power management procedures.
The power consumption during standby mode may be reduced by one of three main factors. One factor is the periodicity of the paging message(s) reception, i.e., DRX cycle duration. However, this periodicity is partly controlled by the network configuration and the need for a reduced latency operation. If a long DRX cycle is used, it may take longer to receive a call or setup a data connection. The second factor is the amount of the leakage power, which may be reduced through advanced integrated circuit design and control techniques. The third factor is the amount of power consumed during the reception of the paging messages.